The present invention relates generally to computer controlled railroad locomotive brake equipment and more specifically to a locomotive brake control unit with dynamic brake interlocks.
The availability of computer controlled railroad brake equipment includes the CCB equipment available from New York Air Brake Corporation. The CCB locomotive brake control equipment is described in U.S. Pat. No. 5,172,316. The numbers used throughout this application correspond to that used in this patent for sake of clarity and consistency.
With the addition of electropneumatic braking and other electric subsections, there has been a proliferation of new on board locomotive subsystems. Since the interconnection of these various subsystems have been added one by one, it has increased the complexity of their interconnection and their weight. The manifold is complex and wiring must be connected to each of the individual electrical valves and transducers. There are thirty-four line replaceable units mounted to the CCB manifold. To provide dynamic braking, the manifold would have to be modified to include a dynamic braking unit. The location of the modification will depend upon whether a resetting or non-resetting dynamic brake response was desired. Adaptor plates were used to incorporate the dynamic brake interlock valves to the manifold and the separate dead-in-tow valves.
Dynamic brake interlock is where the locomotive brakes application resulting from the automatic brake handle or train braking is disabled or released during dynamic braking. In a resetting dynamic brake interlock, the automatic brake application is reapplied once the dynamic braking is terminated. In a non-resetting dynamic brake interlock, the automatic brake application is released and is not reapplied after the termination of the dynamic brake. This protocol is defined by the end user and their preference for dynamic brake operation.
A typical example of prior art devices is the CCB I available from New York Air Brake Corporation. The main manifold includes a first dynamic interlock valve connected between the main reservoir and a pilot valve which provides one of the inputs to a double check valve whose output is the control signal for the brake cylinder relay. The pilot valve is piloted by the actuating pipe known as the 13-pipe. The other input to the double check valve is the automatic or train brake signal. A separate dead-in-tow triple valve not mounted on the manifold, provides a triple valve or back-up brake signal to the manifold for a brake cylinder control and is connected to the independent application and release pipe, or the 20-pipe, the brake pipe and the actuating pipe, or 13-pipe. The dead-in-tow triple valve structure includes a triple valve which controls an auxiliary reservoir as a function of the brake pipe. A pilot valve also controls the auxiliary reservoir in response to the actuating, or 13-pipe. The dead-in-tow triple valve also includes a double check valve which provides the higher value of the 16-pipe or brake signal pipe and the independent application release pipe, or 20-pipe as the triple valve or back-up brake signal to the 16 portion of the main manifold.
Depending upon whether a resetting or non-resetting dynamic brake interlock is required, a second dynamic brake interlock valve is provided in the dead-in-tow triple valve. For the resetting dynamic brake interlock, the magnetic valve disconnects the 16-pipe connection to the double check valve, which provide the triple valve output or back-up brake signal to the manifold. For the non-resetting in the dynamic brake interlock, an electromagnetic valve provides a 16-pipe signal as the control input for the bailoff pilot valve to the double check valve having its other input from the 13-pipe. This bailoff valve is connected to the auxiliary reservoir to bleed the auxiliary reservoir and a back-up brake signal reservoir connected to the dead-in-tow triple valve through operation of the triple valve. A brake signal or 16 reservoir is bled using the electropneumatic controls or the port of the back-up brake signal. For both types of dynamic brake interlock, the first dynamic valve was to disconnect the emergency operation of the brake during interlock.
Thus, there exists a need for a locomotive brake control system capable of being operated with setting or non-resetting dynamic brake interlocks and without dynamic brake interlocks without modification of the manifold.
A locomotive brake control unit, according to the present invention, includes a manifold having a brake cylinder module for controlling pressure at the brake cylinder port in response to at least train braking signals and first and second ports on the control unit for receiving electropneumatic resetting and non-resetting dynamic brake interlocks respectively to control the train braking signals during dynamic braking, if an interlock module is present in one of the interlock ports. The first port on the control unit for the resetting interlock prevents the brake cylinder from applying the brakes during dynamic braking in response to train braking signals and permits the brake cylinder module to reapply the brakes after dynamic braking in response to a train braking signal present before, during and after the dynamic braking. The second port on the control unit for a non-resetting dynamic brake interlock module prevents the brake cylinder from applying the brakes during dynamic braking in response to train braking signals and also prevents the brake cylinder module from reapplying the brakes after the dynamic braking in response to train braking signals present before, during and after the dynamic braking. The brake cylinder module controls pressure at the brake cylinder port during dynamic braking in response to train braking signals and absence of dynamic brake interlock modules in neither of the first or second ports.
The manifold includes an independent brake port and the brake cylinder module controls pressure at the brake cylinder port also in response to pressure at the independent brake port including during dynamic braking. The brake cylinder module includes the relay valve having a control input and a select valve for selecting the higher pressure of the train braking signals and the independent brake port pressure as a control port for the relay. The first or resetting dynamic interlock brake port is on the brake cylinder module between the train braking signal and the select valve.
The manifold also includes an actuating port and the brake cylinder module overrides the train braking signal to release the brakes in response to pressure at the actuating port. A control reservoir is connected to the manifold and the pressure of the control reservoir is the train braking signal. A bailoff valve responsive to a signal on its control input connects the control reservoir to exhaust. The second or non-resetting dynamic brake interlock port is connected to the supply port and a selector valve selects the higher value of the actuating port pressure and the pressure from the non-resetting dynamic brake interlock module in the second port as the control input to the bailoff valve.
The brake control unit also includes an electropneumatic brake signal module mounted on the manifold for providing the train braking signals to the brake cylinder module except when receiving a dynamic brake interlock signal. The first and second ports for the dynamic brake interlocks are on modules on the manifold versus the manifold itself. The control unit includes a pneumatic dead-in-tow module mounted on the manifold which provide a backup pneumatic train brake signal to the brake cylinder module. The second or non-resetting dynamic brake interlock is on the dead-in-tow module and connects the brake signal module and the actuating port.
The circuitry of the locomotive brake control unit has also been changed to allow incorporation of the dynamic brake interlock with a minimum number of parts. The unit includes the brake relay valve having an output connected to the brake cylinder port and having a control input, a first select valve has a pair of inputs connected respectively to the independent brake port and a train brake signal. The first select valve also has an output which is the greater of the inputs and is connected to the control input of the brake relay valve. A triple valve is connected to and responsive to the auxiliary reservoir and brake pipe ports to interconnect an auxiliary reservoir and the brake pipe ports and to provide a back-up brake signal. A bailoff valve selectively connects the backup brake signal or exhaust to its output in response to signals from the actuating port on its control input. A back-up brake signal reservoir port is connected to the output of the bailoff valve. An electropneumatic valve provides an EP brake signal. A second select valve having a pair of inputs receives the output of the bailoff valve and the EP brake signal and selects one of the inputs as an output which is the train brake signal connected to the first select valve. A train brake signal reservoir port is connected to the output of the second select valve.
A resetting electropneumatic dynamic brake interlock valve is connected between the train brake signal and the first select valve. During dynamic brake interlock, it disconnects the train brake signal from the first select valve and therefore only the independent brake signal controls the brake relay valve. For non-resetting a dynamic brake interlock, a third select valve is provided having a pair of inputs connected respectfully to the actuating port and a dynamic brake interlock signal and having an output which is the larger of the two inputs. This output is connected to the control input of the bailoff valve. A non-resetting electrodynamic brake interlock valve is connected and provides a dynamic brake interlock signal to the third select valve. During dynamic brake interlock, the non-resetting dynamic brake interlock valve operates the bailoff valve to disconnect the back-up brake signal from the downstream circuit and exhausts or empties the back-up brake signal reservoir. The output of the bailoff valve or control of the EP brake signal also empties or exhausts the train brake signal reservoir.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.